From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx117.postini.com [74.125.245.117]) by kanga.kvack.org (Postfix) with SMTP id 0A91B6B0107 for ; Sat, 5 May 2012 11:29:25 -0400 (EDT) Received: by yenm8 with SMTP id m8so4954888yen.14 for ; Sat, 05 May 2012 08:29:25 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20120502081705.GB16976@quack.suse.cz> <20120502091837.GC16976@quack.suse.cz> <20120502192325.GA18339@quack.suse.cz> From: KOSAKI Motohiro Date: Sat, 5 May 2012 11:29:03 -0400 Message-ID: Subject: Re: [PATCH] Describe race of direct read and fork for unaligned buffers Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: mtk.manpages@gmail.com Cc: Nick Piggin , Jan Kara , Jeff Moyer , LKML , linux-man@vger.kernel.org, linux-mm@kvack.org, mgorman@suse.de, Andrea Arcangeli , Woodman > So, am I correct to assume that right text to add to the page is as below? > > Nick, can you clarify what you mean by "quiesced"? finished? > > [[ > O_DIRECT IOs should never be run concurrently with fork(2) system call, > when the memory buffer is anonymous memory, or comes from mmap(2) > with MAP_PRIVATE. > > Any such IOs, whether submitted with asynchronous IO interface or from > another thread in the process, should be quiesced before fork(2) is called. > Failure to do so can result in data corruption and undefined behavior in > parent and child processes. > > This restriction does not apply when the memory buffer for the O_DIRECT > IOs comes from mmap(2) with MAP_SHARED or from shmat(2). > Nor does this restriction apply when the memory buffer has been advised > as MADV_DONTFORK with madvise(2), ensuring that it will not be available > to the child after fork(2). > ]] I don't have good English and I can't make editorial check. But at least, I don't find any technical incorrect explanation here. Acked-by: KOSAKI Motohiro -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org